This invention relates to a method for manufacturing a spherical hollow body and more particularly to a method for manufacturing a spherical hollow body, that is, an inner core member for use in the manufacturing of footballs (i.e., soccerballs) or volleyballs.
There have been conventionally proposed various methods for manufacturing a truly spherical hollow ball for football or volleyball. One of the methods for football comprises the steps of forming a spherical hollow body as a core member, sticking cloth strips or rubber sheets with adhesives onto the surface thereof, winding round threads over all the surface thereof, cutting away a predetermined portion thereof to form a small aperture thereon and taking the collapsed pieces out of the hollow ball through the small aperture, inserting a tube with an air valve thereinto and pumping up the tube with air, and sticking outer leather sheets on the surface thereof. According to this specified method, a spherical ball is always produced for football or volleyball if a hollow body is perfectly made spherical. However, it has been difficult to provide a spherical hollow body with a uniform thickness so that there has been a disadvantage that the mechanical strength thereof is weak.
Accordingly, it is a main object of the present invention to provide a method for manufacturing a spherical hollow body having a uniform thickness in such a manner that no skilled person and technology are necessary in the manufacturing thereof.